Liquid rheostat



April 29, 1924. 1,492,430

W. B. CROSSLAND LIQUID RHEOS TAT Filed Oct. 13 1922 Fig; 8)

Fig-1 a7 a E William D Grassland INVENTOR WITNESSES t BY ATTORNEY Patented Apr. 29, 1924.

1 "UNITED STATES PATENT orr cs.

WILLIAM'BLACKNELI. OROSSLAND, or PHILADELPHIA, PENNSYLVANIA.

' LIQUID RHEOSTAT.

Application me October 13, 1922- Serial No. 594,318.

1 all whom it may concern:

Be itvknown that I, WILLIAM Cross- LAND, aicitizen of the United States, [residin at Philadelphia, in the county of Philadelphia and State of Pennsylvania,have inventeda new and useful Liquid Rheostat, of

which the following is a specification.

1 My invention relates to a liquid rheostat, which is automatically operated upon the closing of a switch in the circuit to increase the flow of current gradually until the maximum is reached.

When used in connection with tungsten lamp circuits, my, invention prevents the 15, violent jerk to the filament which is caused whenever thefull current is turned on suddenly. .When used in connection with a motor, it compels a slow and even start, protects the fuses, and reduces starting trouble to a minimum. It alsoa'cts as a cut-out when the voltage in the circuit falls below a certain predetermined point.

The general object of my invention is to provide a rheostat which will accomplish the results outlined above, which will be reliable in operation and inexpensiveto manufacture, which maybe cut into the circuit at any point, and controlled by a switch which-may be locatedat a remote point, and which, when once installed, will require no further attention for many years.

My invention will be best understood from the following description, taken in connection with'the accompanying drawing, which illustrates one way in which the invention may be carried out. Y I In the drawing- I I Fig. 1 is aside elevation of the invention; Fig. 2 is a rear elevation thereof; 9 Fig. 3 is a vertical longitudinal section on 1 the line 33 of Fig. 2; c I I Fig. 4 is a plan view of the invention. In carrying out my invention, '1' provlde a jar 1, preferably of glass, and provided withv a cover 2 which is made substantially airtight. Secured tothe rear side of the jar is a shelf or bracket 3, on which are supported a air of electro-magnets 4 andc5, the shelf 3 eing supported by means of a shoulder 6' in close contact-with the rear side of the 'ar, and ears or brackets 7 which extend along the sides of the jar and are secured to a spindle 8 that extends through the jar and is cemented'to the side walls thereof. The spindle within the jar,

is enlarged to form a core 9, which is preferably square in crosssection, and composed of soft iron. surrounded by a thin jacket 10 of brass or other non-corrosive material, and which forms an electrode. The other electrode 11, composed of iron, is secured to the lower edge of a conductingelement 12 which is shown in the shape of a quadrant secured to a sleeve 13, loosely mounted on a spindle 14, extending across and see cured to the walls of the jar. The element 12isnormally' heldin the position shown in Fig. 1, by means of a flexible cord 15, or the like, which is wound around the sleeve 13, and passes therefrom upwardly through an opening 12 in the element 12, and is secured at its upper end to the end of the stem 16 above the jar. When the stem 16 is lowered, the element 12 will gravitate downwardly to the position shown in Fig. 3..

The stem 16 has a vertical portion which is guided by a bracket 17 secured between the magnets, and by an insulating sleeve 18 threaded into the shelf 3. The stem is moved upwardly and downwardly by means of pins 19 secured transversely of the stem, and guided in the slots 20 formed in the armatures 21, which are supported by leaf springs 22 from the washers 23 of the magnets and in operative relation to the latter.

The device is connected to the line wire 24, which is provided with a switch 25, and wire 26 extending to a binding post 27, formed on the end of the spindle 14, at one side of the jar. The other line wire 29 is connected to one terminal of the magnets,

the other terminal being connected through a wire 28 to one end of the spindle 8.

In. theoperation of the rheostat, when the. switch 25 is closed, the initial current passes through the wire 26, spindle 14, sleeve 13, and element 12, to the electrode 11. The element being initially in the position shown in Fig. 1, only a minimum amount of cur rent will pass through the liquid in the jar to the electrode 9. The current will pass thence through wire 28 and the magnets 5 and 4, respectively, to the line wire 29. The initial current will energize the magnets sufficiently so that. the armatures 21 will be drawn into contact with the cores 30 against the resistance of the springs 22. The stem 16 will thereby be lowered to the position .shown in Fig. .3, thus slackening the cord 15 and permitting the element 12 to gravitate slowly downwardly until it finally reaches the position shown in Fig. 3. The core of the electrode 9 is located within the magnetic field set up by the energization of the electro-magnets, and, particularly after the parts are in the position shown in Fig. 3, where the maximum current will be reached, the magnetic attraction between the electrodes will be sufficient to insure a close, firm contact.

when the switch 25 is opened, the magnets becoine dead, the armatures are released, and the element 12 is raised again to its initial position. Also, preferably, the springs 22 are made of sufficient strength so thatwhen the voltage in the line reaches a predetermined minimum, they will overcome the attraction of the magnets and act as a cut-out.

The initial amount of current which passes through the magnets when the switch 25 is closed, must be sufficient to energize the magnets enough to overcome the springs 22. This amount is obtained by properly regulating the conductivity of the liquid in the jar; for example, for 2500 watt load, the liquid is so prepared that only 300 watts will pass therethrough, this amount being sufficient to set up a magnetic field that will overcome the springs 22.

From the foregoing description, it will be seen that this invention when placed anywhere in the line, will always insure a gradual introduction of current whenever the switch is turned on. The switch may be located at a remote point, and the action of the rheostat r entirely automatic and beyond the audition of the operator, and in fact, may be used without his knowledge. The conta-.-.s are magnetic, thus insuring a full and complete contact: at all times. The contaiiu-r is n'iade of glass, so that its condition can be observed from time to time, and is practically airtight, so that evaporation is prevented and the original liquid should last or many years, since it is hardly disturbed by the operation.

When used in connection with the lamps now in general use, it will prolong the life and brilliance thereot, and will make ossible the common use of lamps of hig er. cfiiciency than has hitherto been attempted.

hen used in connection with electric motors, it will compel a slow and even start, preventing the sudden in rush of current which is destructive to the fuses, and will therefore reduce motor starting troubles to a minimun'i.

It will also solve the problem which confronts the makers of motion picture lighting apparatus.

The rheostat will, of course, be made in dil ferent sizes according to the use for which it is designed. and by making the jar longer,

the number of magnets and likewise the number of elements may be increased as desired. It will also be understood that while I have shown and described one specific embodiment of my invention, the same is capable of many modifications within the scope of the appended claims.

lVhat is claimed is 1. In a device of the character described, a pair of electrodes normally separated by a gap filled with liquid of relatively low conductivity and operable by the initial current passing therethrough to completely close the gap and establish a firm contact between the electrodes.

2. In a device of the character described, a pair of electrodes normally separated by a gap filled with a liquid of relatively low conductivity, an electro-magnet energized by the initial current passing through the liquid, and means set in operation by said magnet to completely close the gap and establish a firm contact between the electrodes.

3. In a device of the character described, a pair of electrodes normally separated by a gap filled with a liquid of relatively low conductivity, one of said electrodes being movable by gravity toward the other electrode, and means normally overcoming such gravitation, the initial current through the electrodes being capable of releasing said means to permit the movable electrode to gravitate.

4. In a device of the character described, a pair of electrodes normally separated by a gap filled with a liquid of relatively low conductivity, one of said electrodes being movable by gravity toward the other electrode, means normally overcoming such gravity, and means actuated by the initial current through the electrodes to release the first-named means and permit the movable electrode to gravitate.

5. In a device of the character described. a jar containing liquid, a fixed electrode immersed in the liquid, a second electrode pivotally mounted and normally held above the fixed electrode and adapted when released to gravitate about its pivot towards the fixed electrode, a switch. and means actuated by the turning oil the switch to release said pivoted electrode.

6. In a device of the character described, a jar containing liquid, a fixed electrode immersed in the liquid, a movable electrode, a switch, means operable by the closing of the switch to cause the movable electrode to move toward the fixed electrode, and means for causing the movable electrode to move away from the fixed electrode when the voltage of the line falls below a predetermined minimum.

7. In a device of the character described, a jar containing liquid, a fixed electrode immersed in the liquid, a second electrode movabletowardand away from the fixed electrode, a switch, and'an electro-magnet operable, when the switch is turned on, to cause said second electrode to movetoward the fixed electrode. I

8. In a device of the character described, a jar containing liquid, a fixed electrode immersed in the li uid, a second electrode movable toward an away from the fixed elec trode, a switch, and an electro-magnct operable, when the switch is turned on, to cause said second electrode to move toward the fixed electrode, said fixed electrode being within the magnetic field set up by the electric current andenergized thereby.

9. In a device of the character described, a pair of electrodes normally separated by a gap filled with liquid of relatively low conductivity, a switch operable to close the circuit through the electrodes and liquid, an electro-magnet energized by this initial current and operable when energized to close the gap between the electrodes, said magnet being also operable to set up a magnetic attraction between the electrodes when closed.

10. In a device of the character described,

' a pair of electrodes normally separated by a gap filled with a liquid of relatively low conductivity, one of said electrodes being movable by gravity toward the other electrode, an electro-magnet having a springheld armature, means actuated by the armatime under action of the spring to overcome the action of gravity on the movable electrode, and a switch for turning current through the electrodes, liquid and electromagnet,the latter whenso energized overcoming the action of the springto permit the movable electrode to gravitate.

11. In a liquid rheostat, a fixed electrode in the form of a separate bar immersed in liquid, a spindle located above and parallel to the fixed electrode and havinga binding post at one end, a conductor element loosely mounted on the spindle and having a bar constituting a movable electrode adapted to swing by gravity into contact with the fixed electrode but normally held'in its uppermost position, a switch and means actuated by the switch to release the conductor element and permit the same to gravitate until the electrodes form a contact.

12. In a liquid rheostat, a jar containing liquid, a bar supported horizontally in the liquid and forming a fixed electrode, a spin dle located above and parallel to the fixed electrode, a conductor element comprising a sleeve loosely mounted on the spindle, and a bar carried by the sleeve and constituting a movable electrode adapted to swing about the spindle into contact with the fixed electrode, springheld means to normally overcome gravity and hold the conductor element in its uppermost position, a switch and means actuated by the switch to release 13.-In'a liquid rheostat, a fixed electrode in the form of a separate bar immersed in liquid, a spindle located above and parallel to the fixed electrode and having a binding post at one end, a conductor element in the shapeof a quadrant loosely mounted on the spindle and having a bar constituting a movable elect-rode adapted to swing by gravity into contact with the fixed electrode but normally held in its uppermost position, a switch and electro-magnetic means operable by the initial current through the liquid when the switch is turned on to release the conductor element and permit the same to gravitate until the electrodes form a contact;

14. In a liquid rheostat, a jar containing liquid, a bar supported in the walls of the jar and forming an electrode immersed in the liquid, a spindle located above and parallel to the bar and having a binding post at one end, a conductor element comprising a sleeve loosely mounted on the spindle, and a bar secured to the sleeve and constituting a movable electrode adapted to swing by gravity about the spindle into contact with the fixed electrode, spring-held means to normally overcome gravity and hold the conductor element in its uppermost position, a. switch and electro-magnetic means operable by the initial current through the liquid when the switch is turned on to release the conductor element and permit the same to gravitate until the electrodes form a contact.

15. In a liquid rheostat, a jar containing liquid, a fixed electrode in the form of a separate bar immersed in theliquid and supported by. the walls of the jar, a spindle locatedabove and parallel to the fixed electrode and having a binding post at one end,

a conductor element loosely mounted on the no spindle and having a bar constituting a movable electrode adapted to swing by gravity into contact with the fixed electrode, a stem mounted for vertical movement and flexibly connected to the conductor element and normally holding the latter in its up permost position, a switch, and means onerable by the initial current through the liquid when the switch is turned on to lower said stern and permit the conductor element to gravitate until the electrodes form a contact.

16. In a liquid rheostat, a jar containing liquid, a fixed electrode in the form of a separate bar immersed in the liquid and supported by the walls of the jar, a spindle located above and parallel to the fixed electrode and having a binding post at one end,

a conductor element loosely mounted on the spindle and having a bar constituting a l movable electrode adapt-ed to swing by gravity into contact with the fixed electrode, a stern mounted for vertical movement and flexibly connected to the conductor element and normally holding the latter in its uppermost position, a switch, a pair oil? electro-magnets in the line connected to one of the electrodes and having; spring-held armatures the normal initial current through the liquid when the switch is turned on being sufiicient to close said armatures, and pinand-slot connections between said armatures and said stem whereby the latter is moved downwardlv by a closure of the ari'natures to release the conductor element and permit it to gravitate until the electrodes form a contact.

In testimony that I claim the foregoing as my own, I have hereto aflixed my signature.

WILLIAM BLACKNELL CROSSLAND. 

